The present invention relates to emitting and sensing acoustical or mechanical vibration, concurrently while receiving and transmitting electrical signals corresponding to a vibration state parameter. In particular, the invention relates to a mechano-electrical transducer for emitting and sensing vibration, and for concurrent reception and transmission of at least one electrical signal that corresponds to the emitted or sensed vibration.
Transducers between electrical and mechanical energy (vibrations, force, acceleration) have many uses, and exist in various implementations. Often, two or three separate transducers are used, for example, sense acceleration in three orthogonal directions, by suspending massive bodies in springing systems so that they move relative to respective reference frameworks.
GB 2,055,018 and EP 118,329 teach known transducers with a massive body suspended centrally in piezoelectric flexible xe2x80x9clamellasxe2x80x9d, or in piezoelectric filaments, for seismic and acoustical detection applications.
Related art can also be found in GB 2,166,022, which teaches a transducer in the form of a loudspeaker (i.e., providing transformation from electrical to acoustical signals) and a massive body suspended centrally in a piezoelectric thin loudspeaker diaphragm that may be divided into several lamella-like areas by radial slits. Since it is common knowledge that a loudspeaker can also be utilized as a microphone, the GB 2,055,018 publication must be regarded as showing a bidirectional transducer. The point of the central body in the publication is that it will be possible to lower the useful frequency range of the loudspeaker by adding such a center mass.
The present invention aims at providing a bidirectional transducer that, better than previously known solutions, is able to operate with a directional effect and provide improved emission and detection, particularly in connection with echo measurements in biological tissue.
Hence, in accordance with the invention there is provided a mechanoelectric two-way transducer as described below. Preferable embodiments of the invention are also described below.